Polymer electrolytes based on POE and Na-TFS salt for all-solid-state batteries

Purpose: Currently, electrochemical energy storage systems mostly focus on lithiumion batteries; especially in the field of portable electronics and electric transportation. Nevertheless, it is expected that the exponential growth of these markets and limited lithium resources will increase the price of lithium-based energy storage systems. To meet growing demands in terms of green and sustainable electric power storage, alternative electrochemical technologies towards post lithium-ion batteries are required. Design/methodology/approach: In the present study, polymer electrolytes based on poly(oxyethylene) (POE) and Na-TFS (NaCF3SO3) were developed to be used in solventfree batteries. Electrolytes were prepared using two methodologies: (i) a green-chemistry approach based on lyophilization combined with hot-pressing and (ii) the film-casting method. Findings: Advantages and limitations of both approaches were investigated by several characterization techniques (morphology, thermal and conductivity studies). Using lyophilization/hot-pressing, waste and chemical derivatives production is prevented (Green Chemistry approach) and uniform and porous-free films with controllable thickness and improved mechanical properties are achievable. Research limitations/implications: Further work regarding the development and application of novel polymer backbones is necessary to reach performances comparable to lithium-based polymer electrolytes in terms of electrical properties (conductivity). Originality/value: This work is in total agreement with the current need of developing alternative materials towards sustainable and environmental friendly post lithium-ion batteries. This global aspiration is supported by the recent re-emerging focus on sodium-ion batteries.